Abstract
Nowadays, the arsenic pollutant in groundwater is a serious problem in the world. In Cambodia, the ratio of the water-supply system coverage is 14 % and the sewage system coverage is 11 %, and due to this conditions, it is estimated that people utilize untreated well-water as their domestic water and directly drain the raw sewage to the surrounding of their houses. In addition, Mekong river inundates in Cambodia every year. Therefore, the surface water is possibly polluted by arsenic and arsenic is diffused in the surface water. In this study, in order to estimate the arsenic concentration in the surface water in Cambodia, we propose a new simulation model. This model is composed from a flood-inundation model, a transport of suspended sediment model and a transport arsenic model. We chose the parameters in this model from the data acquired by the field survey in Cambodia.
The result of the arsenic concentration in the surface water obtained from the numerical simulation model was close to the almost digit of the result of the field survey in the rainy season. The simulation results suggested that during the rainy season, arsenic in the surface water is widely spreaded in the inundate area. On the other hands, in the dry season, the arsenic concentration in the surface water increases before the dry season. In Camnodia, the inundation of Mekong river happens every year. Therefore, we estimate that the arsenic concentration in the surface water may increase furthermore in the future.
